In an effort to gain a better understanding of human VEP components and their possible physiological origin, we propose to use the alert monkey (Macaca fascicularis) as an animal model. Steady state and transient visual evoked potential recordings will be made in response to systematic stimulus variations of spatial frequency, temporal frequency, contrast, duration, disparity, and movement. The aim is both to determine the degree to which the responses are similar to human VEPs obtained from the same stimuli, as well as to differentiate and isolate separate VEP components. Both surface and depth recordings will be made, and for better specification of the depth response, we shall use techniques similar to those used for current source density analysis.